[PATCH v8 3/5] usb: gadget: Add function wakeup support

[Elson Roy Serrao]

USB3.2 spec section 9.2.5.4 quotes that a function may signal that
it wants to exit from Function Suspend by sending a Function
Wake Notification to the host if it is enabled for function
remote wakeup. Add an api in composite layer that can be used
by the function drivers to support this feature. Also expose
a gadget op so that composite layer can trigger a wakeup request
to the UDC driver.

Reviewed-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
---
 drivers/usb/gadget/composite.c | 40 ++++++++++++++++++++++++++++++++++++++++
 include/linux/usb/composite.h  |  6 ++++++
 include/linux/usb/gadget.h     |  1 +
 3 files changed, 47 insertions(+)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index c9c983e..2111732 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -492,6 +492,46 @@ int usb_interface_id(struct usb_configuration *config,
 }
 EXPORT_SYMBOL_GPL(usb_interface_id);
 
+/**
+ * usb_func_wakeup - sends function wake notification to the host.
+ * @func: function that sends the remote wakeup notification.
+ *
+ * Applicable to devices operating at enhanced superspeed when usb
+ * functions are put in function suspend state and armed for function
+ * remote wakeup. On completion, function wake notification is sent. If
+ * the device is in low power state it tries to bring the device to active
+ * state before sending the wake notification. Since it is a synchronous
+ * call, caller must take care of not calling it in interrupt context.
+ * For devices operating at lower speeds  returns negative errno.
+ *
+ * Returns zero on success, else negative errno.
+ */
+int usb_func_wakeup(struct usb_function *func)
+{
+	struct usb_gadget	*gadget = func->config->cdev->gadget;
+	int			id;
+
+	if (!gadget->ops->func_wakeup)
+		return -EOPNOTSUPP;
+
+	if (!func->func_wakeup_armed) {
+		ERROR(func->config->cdev, "not armed for func remote wakeup\n");
+		return -EINVAL;
+	}
+
+	for (id = 0; id < MAX_CONFIG_INTERFACES; id++)
+		if (func->config->interface[id] == func)
+			break;
+
+	if (id == MAX_CONFIG_INTERFACES) {
+		ERROR(func->config->cdev, "Invalid function\n");
+		return -EINVAL;
+	}
+
+	return gadget->ops->func_wakeup(gadget, id);
+}
+EXPORT_SYMBOL_GPL(usb_func_wakeup);
+
 static u8 encode_bMaxPower(enum usb_device_speed speed,
 		struct usb_configuration *c)
 {
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index d949e91..a2448e9 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -150,6 +150,9 @@ struct usb_os_desc_table {
  *	GetStatus() request when the recipient is Interface.
  * @func_suspend: callback to be called when
  *	SetFeature(FUNCTION_SUSPEND) is reseived
+ * @func_suspended: Indicates whether the function is in function suspend state.
+ * @func_wakeup_armed: Indicates whether the function is armed by the host for
+ *	wakeup signaling.
  *
  * A single USB function uses one or more interfaces, and should in most
  * cases support operation at both full and high speeds.  Each function is
@@ -220,6 +223,8 @@ struct usb_function {
 	int			(*get_status)(struct usb_function *);
 	int			(*func_suspend)(struct usb_function *,
 						u8 suspend_opt);
+	bool			func_suspended;
+	bool			func_wakeup_armed;
 	/* private: */
 	/* internals */
 	struct list_head		list;
@@ -241,6 +246,7 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g, struct usb_function *f,
 
 int config_ep_by_speed(struct usb_gadget *g, struct usb_function *f,
 			struct usb_ep *_ep);
+int usb_func_wakeup(struct usb_function *func);
 
 #define	MAX_CONFIG_INTERFACES		16	/* arbitrary; max 255 */
 
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 1d79612..75bda078 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -310,6 +310,7 @@ struct usb_udc;
 struct usb_gadget_ops {
 	int	(*get_frame)(struct usb_gadget *);
 	int	(*wakeup)(struct usb_gadget *);
+	int	(*func_wakeup)(struct usb_gadget *gadget, int intf_id);
 	int	(*set_remote_wakeup)(struct usb_gadget *, int set);
 	int	(*set_selfpowered) (struct usb_gadget *, int is_selfpowered);
 	int	(*vbus_session) (struct usb_gadget *, int is_active);
-- 
2.7.4